Q. Why does the NFU oppose vaccination for Foot and Mouth Disease (FMD) but support it for the Bluetongue Virus (BTV)?

A. The NFU does not oppose vaccination for FMD: we agree that it should be available as part of the control strategy and would support its use, if this is what veterinary and scientific advice recommended. Each disease outbreak is different.

In 2001 vaccination was considered, but only for cattle and in certain specific locations, but veterinary opinion was divided and this approach was not pursued.

We opposed vaccination in the very widespread 2001 outbreak because no one could demonstrate that vaccination would bring the disease under control more quickly or that fewer animals would be culled as a result (this view was subsequently endorsed by the Government Chief Scientist).

Veterinary advice in the localised 2007 outbreak has, so far, been that it would not help to eradicate the disease.

Vaccines are available against the various known strains of FMD. In the case of BTV there are vaccines for some strains, but not for the BT serotype 8 virus that has been identified in East Anglia. One is being developed but has not yet been fully tested and approved. It is hoped that it will be available before next summer.

In the case of BTV there are a number of factors that make vaccination more likely to be a regular part of the means of control and eradication.

• FMD is a highly contagious virus that is transmitted easily between susceptible species and cannot live for long periods outside a host. It is relatively easy to kill the virus and its spread can be prevented or reduced by strict bio-security.
  
  BTV is transmitted from particular species of midges to susceptible animals (cows, sheep and goats). It is NOT transmitted from animal to animal, so culling could not be an effective eradication strategy, once the disease is established in the midge population. Equally, there are no bio-security measures that can eliminate, or even significantly reduce, its spread.
  
  
• FMD can be controlled and eradicated relatively quickly by culling and bio-security measures alone. Once BTV has been identified, it would require a country or a region to go through two seasons with no further cases to be declared disease free.
  
  Given that, once established, the disease is likely to be circulating in the midge population it is highly likely that BTV would become permanently established in the cattle and sheep population. Vaccination is the only answer.
  
  
• There are many different strains of FMD virus, and a specific vaccine is required for each strain. BT is a disease traditionally found in North Africa/ Southern Europe where a number of different serotypes have been identified.
  
  Its incursion into North West Europe in 2006 was the first recorded incidence in these latitudes. So far, only one strain, BTV8, has been identified in Northern Europe. This makes preventative vaccination a much more feasible option.
  
  
• It takes longer to remove trade restrictions in live animals from a country or zone that has used vaccination against FMD. In the case of BTV the vaccine that is being developed would allow you to distinguish between an animal that had been vaccinated and one exposed to the virus.
  
  The EU regulations concerning BTV are being reviewed and there would be an opportunity to allow trade in vaccinated animals, Even if this is not possible, BTV is now established in France, Germany, Belgium, Luxembourg and the Netherlands (possibly Denmark) so trade in vaccinated animals in this zone would be possible.
  
  
• FMD vaccines are live- so there is always a risk of a vaccine actually causing disease. The BTV vaccine under development is inactive, which has a number of advantages.
  
  
• There are severe practical difficulties in vaccinating pigs against FMD; if you vaccinate pigs that have already contracted the disease it masks the symptoms at a time when pigs are emitting vast quantities of the virus. There would therefore be difficulties about pigs- particularly outdoor pigs- in an FMD outbreak. BTV does not affect pigs, so same problems don't exist.

Conclusion

For all these reasons, the NFU supports vaccination as the most promising means of controlling and eliminating BTV, but it would be wrong to give the impression that vaccination is a simple solution, and there are many practical problems to be resolved.

No vaccine is currently available and we do not know how effective it will be at farm level for both cattle and sheep, or for how long the vaccine will give protection.

To give full protection to the national herd and flock it would be necessary to ensure that all cattle and sheep were vaccinated, and recorded. This is much easier in the case of cattle than sheep.

TheCattleSite News Desk